Without limiting the scope of the present invention, its background will be described with reference to producing fluid from a hydrocarbon bearing subterranean formation, as an example.
During the completion of a well that traverses a hydrocarbon bearing subterranean formation, production tubing and various completion equipment are installed in the well to enable safe and efficient production of the formation fluids. For example, to prevent the production of particulate material from an unconsolidated or loosely consolidated subterranean formation, certain completions include one or more sand control screen assemblies positioned proximate the desired production interval or intervals. In other completions, to control the flow of production fluids into the production tubing, it is common practice to install one or more flow control devices within the tubing string.
Attempts have been made to utilize fluid flow control devices within completions requiring sand control. For example, in certain sand control screens, after production fluids flows through the filter medium, the fluids are directed into a flow control section. The flow control section may include one or more flow control components such as flow tubes, nozzles, labyrinths or the like. Typically, the production flowrate through these flow control screens is fixed prior to installation by the number and design of the flow control components.
It has been found that certain completions utilizing such flow control screens may benefit from a stimulation treatment prior to production. For example, in one type of stimulation treatment, a fluid containing a reactive acid, such as hydrochloric acid, may be injected into the reservoir formation. Such acid stimulation treatments are designed to improve the formation permeability which enhances production of reservoir fluids. Typically, acid stimulation treatments are performed by injecting the treatment fluid at a high flowrate and at a treatment pressure near but below the fracture pressure of the formation. This type of protocol enables the acid to penetrate the formation but avoids causing damage to the reservoir formation.
It has been found, however, that achieving the desired injection flowrate and pressure profile by reverse flow through conventional flow control screens is impracticable. As the flow control components are designed for production flowrates, attempting to reverse flow through conventional flow control components at injection flowrates causes an unacceptable pressure drop. In addition, it has been found that the high velocity of the injection fluids through conventional flow control components may result in erosion within the flow control components. Further, it has been found that achieving the desired injection pressure may require exceeding the pressure rating of conventional flow control components during the treatment operation.
Accordingly, a need has arisen for a flow control screen that is operable to control the inflow of formation fluids in a completion requiring sand control. A need has also arisen for such a flow control screen that is operable to allow reverse flow from the completion string into the formation at the desired injection flowrate without creating an unacceptable pressure drop. Further, need has also arisen for such a flow control screen that is operable to allow reverse flow from the completion string into the formation at the desired injection flowrate without causing erosion within the flow control components and without exceeding the pressure rating of the flow control components during the treatment operation.